Plant Doctor Archive

What can I plant in my clay soil?

Question I HAVE a corner of my section which has heavy clay soil with poor drainage. I have applied compost for about three years now and the soil is beginning to show signs of improvement. However, I am looking for a suitable tree to grow in these conditions, preferably an evergreen as we hope to put a pool in this area in the near future.

Answer WITHOUT knowing how high you would like the tree to grow and whether the area is frost prone, here are a few suggestions:

Magnolia grandiflora — grows to about 7 metres high, is slow growing, has spectacular creamy-white, fragrant flowers. Magnolia grandiflora ‘Little Gem’ also has lovely creamy-white flowers and only grows to a height of 3 metres. Both have lovely foliage.

Sophora microphylla (Kōwhai) — there are several varieties growing from 1.2 metres up to 5 metres. However, the flowers do drop and could become a problem when the pool is installed.

Pseudopanax (Lancewood or Five Finger) — another evergreen NZ native which is extremely hardy. There are variegated forms to add interest.

Metrosideros (Pōhutukawa) — various cultivars are available, including yellow flowered and variegated forms. Which variety you choose would depend upon the final height you want it to grow to.

Gordonia axillaris — may also be a possibility. It has lovely creamy-white flowers and clusters of yellow stamens. It flowers in winter and grows to a height of 3 metres. Gordonias are slow growing.

Grevillea — there are several varieties of Grevillea that grow from 2 to 3 metres in height. They have attractive spider-like flowers and are extremely hardy.

Griselinia littoralis or G. lucida — NZ natives worthy of a look.

Cupressocyparis leylandii — a fast growing conifer with attractive foliage. Grows to a height of 5 metres.

This list is by no means comprehensive and is only a starting point — your local garden centre can help with trees suited to your local conditions.

It may be worth looking at planting into a raised bed to improve drainage, or using gypsum to help break down the clay soil. Gypsum comes in a powder form, is a type of lime and is also available in a liquid form.

Meanwhile, keep adding compost, peat or as much well-rotted organic material to the soil as you can.